Chapter 4 Study Questions

Chemistry 110
Chapter 4 – Chemical Bonding: The Ionic Bond Model
Study Questions
Each question is worth 0.2 points. Total assignment is worth 5 points.

1. Describe the characteristics of ionic compounds and of molecular compounds. Ionic compounds have high melting points and conduct electricity well while covalent molecules have lower melting points and will not conduct electricity in a liquid state.

2. What types of particles are present as ionic bonds? Molecular compounds?
Ionic bonding occurs between charged particles. These may be atoms or groups of atoms, but this discuss will be conducted in terms of single atoms. Ionic bonding occurs between metal atoms and nonmetal atoms. Molecular compounds form as a result of covalent bonding where electrons are shared between non-metal atoms.

3. What is a chemical bond? Discuss the differences between an ionic bond and a covalent bond.
Any of several forces, especially the ionic bond, covalent bond, and metallic bond, by which atoms or ions are bound in a molecule or crystal. Ionic bonds are chemical bonds between two ions with opposite charges, characteristic of salts. Covalent bonds are chemical bond formed by the sharing of one or more electrons, especially pairs of electrons, between atoms.

4. What are valence electrons? Electrons in an outer shell of an atom that can participate in forming chemical bonds with other atoms.

5. What is a Lewis Structure?
A diagram that shows the bonding between atoms of a molecule and the lone pairs of electrons may exist in the molecule.

6. List the three generalizations about valence structures.
1.Representative elements in the same group have the same number of valence electrons.
2.The number of valence electrons for representative elements is the same as the Roman numeral periodic-table number.
3.The maximum number of valence electrons for any element is eight.

7. How many valence electrons are present for : a. Oxygen (6) b. Sodium (1) c. Chlorine (7)

8. State the octet rule.
In forming compounds, atoms of elements lose, gain, or share electrons in such a way as to produce a noble-gas electron configuration for each of the atoms involved.

9. Which group of elements are the most unreactive? Why?
The Noble Gases are the most unreactive. Their outermost electron layer is completely filled (8 electrons present) so they are very stable and unreactive.

10. What is an ion?
An ion is an atom or a group of atoms that has acquired a net electric charge by gaining or losing one or more electrons

11. What charge will result on an ion if the atom gains electrons? If the atom looses electrons?
The ion will have a negative charge it gains electrons, and a positive charge if it looses electrons.

12. What has been the change in the number of electrons for an atom that has a: a. +2 charge = lost 2 electrons b. -3 charge = gained 3 electrons c. + charge = lost 1 electron d. -2 charge = gained 2 electrons 13. In what group will an element be found that has the following charge: a. +2 = 2A b. -3 = 5A c. – = 7A d. -2 = 6A 14. Explain how electron transfer forms an ionic compound.
One atom must donate (a metal) an electron and one must accept (a nonmetal) the electron, and they will create a neutral ionic compound

15. What is the charge on an ionic compound?
Neutral (0)

16. List the three rules for writing an ionic compound.
1.The symbol for the positive ions is always written first.
2.The charges on the ions that are present are not shown in the formula.
3.The subscripts in the formula give the combining ratio for the ions.

17. Write the compound for each of the following pairs of elements: a. Na+ + Cl- = NaCl b. I- + Ca+2 = CaI2 18. Describe the composition of a binary ionic compound.
Metal-nonmetal = Metal is always present as the positive ion, and the nonmetal is always present as the negative ion.

19. Name the following compounds a. MgCl2 = Magnesium chloride b. NaI = Sodium iodide c. LiBr2= Lithium bromide d. KCl = Potassium chloride

20. List the metallic elements that have a fixed ionic charge.
Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ag, Zn, Cd, Al, Ga

21. Discuss the difference between a single covalent bond, a double covalent bond and a triple covalent bond. How are single, double and triple bonds notated?
Most single covalent bonds are formed between two nonmetals when two electrons, or one pair of electrons, are shared between two atoms and are notated by 1 pair of dots between the elements in the drawing. If two pairs of electrons are shared, the bond is called a double covalent bond. 2 pairs of dots between the elements in the drawing notate double covalent bonds. If three pairs of electrons are shared, the bond is called a triple covalent bond and is notated by 3 pairs of dots between the elements in the drawing.

22. When drawing Lewis structures, how many electrons must each element have surrounding it?
Each element only needs to have the number of electrons around it that naturally represent the charge of the element. This means that each element will display between 1 and 7 electrons.

23. What is a polyatomic ion?
Polyatomic ions are formed when a group of atoms are held together by covalent bonds and has a charge associated with it.

24. Explain how ionic and covalent bonds are present with polyatomic ions.
Polyatomic ions are formed when a group of atoms are held together by covalent bonds and has a charge associated with it (ionic bonds).

25. Write the formulas for the compounds formed between the following ions: a. Na+ and OH- = 1 Na+ + 1 OH- = NaOH b. Mg+2 and CO32- = 1 Mg+2 + 1 CO32- = MgCO3 c. Ca+2 and ClO3- = Ca(ClO3)2 d. Li+ and PO43- = Li3PO4